The present invention relates generally to an apparatus for referencing a workpiece to a worktable and, in particular, to an apparatus for providing a Y-axis reference for a vertical milling machine.
A milling machine is a machine tool that removes metal as the work is fed against a rotating cutter. Except for rotation, the circular-shaped cutter has no other motion. It is called a milling cutter and has a series of cutting edges on its circumference, each of which acts as an individual cutter in the cycle of rotation. The work is held on a table which controls the feed against the cutter. In most milling machines, there are three possible table movements, longitudinal, cross-wise and vertical, but in some machines, the table can also swivel or rotate.
The milling machine is the most versatile of all machine tools. Flat or formed surfaces can be machined with excellent finish and great accuracy. Angles, slots, gear teeth and recess cuts can be made by using various cutters. Drills, reamers, and boring tools can be held in the arbor socket by removing the cutter and arbor. Since all table movements have micrometer adjustments, holes and other cuts can be accurately spaced. Most operations performed on shapers, drill presses, gear-cutting machines, and broaching machines can likewise be done on the milling machine. It produces a better finish and holds to accurate limits with greater ease than a shaper. Heavy cuts can be taken with no appreciable sacrifice in finish or accuracy. Cutters are efficient in their action and can be used a long time before being resharpened. In most cases, the work is completed in one pass of the table. These advantages, plus the availability of a wide variety of cutters, make the milling machine indispensable in the machine shop and tool room.
A typical vertical milling machine is so called because of the vertical position of the cutter spindle. The table movements are the same as in plane machines. Ordinarily, no movement is given to the cutter other than the usual rotational motion. However, the spindle head can be swiveled, which permits setting the spindle in a vertical plane at any angle from vertical to horizontal. This machine is also provided with a short axle spindle travel to facilitate step milling. Some vertical milling machines are provided with rotary attachments or rotating worktables to permit the milling of circular grooves or continuous milling of small production parts. Cutters are all of the end-mill type.
Uses of the machine include drilling, boring, and reaming, accurate spacing of holes because of the micrometer adjustment of the table, facing cuts, and finishing in recesses. Profiling and die-sinking machines are very similar to vertical milling machines in their operation.
In order to accurately position the workpiece on the worktable with respect to the cutter, the table is often provided with one or more generally T-shaped slots for engaging various stops and clamps. However, the tolerances on the slot opening and the tolerances on stops or clamps which engage the slots many times make it impossible to position the workpiece with the accuracy required to form a finished part.